In this paper, winding function method (WFM), applied to a faulted synchronous generator, is modified and is used for on-line diagnosis of mixed eccentricity fault. For the first time, the static and mixed eccentricities are modeled in synchronous generators. A modified winding function (MWF) method introduced here is more precise compared with previous methods. This MWF enables to compute the air gap magnetic permeance accurately. Here, two or three terms of the infinity permeance series has not been used, but a closed form equation is employed for permeance evaluation. This leads to a very precise computation of the inductances of the faulted machine. Self inductances of the stator and rotor, mutual inductance of two stator phases and the mutual inductance of rotor and stator are obtained. Meanwhile, it is shown that static, dynamic and mixed eccentricities lead to the increase of the amplitude and occurrence of the distortion in the aforementioned inductances. Since calculation of inductances is the most important step for fault diagnosis of the machine, the proposed method improves the on-line diagnosis of the fault. Meanwhile, the spectrum analysis of stator current, obtained from experimental results, is illustrated.

An innovative method for antenna arrays beam configuration is presented. In the proposed method, every element of the array is connected to its feed through a switch, so that it can be active or passive, depending on the switch position. Pattern reconfigurability is achieved by appropriately switching on or off the array elements. The optimal configuration of the switches for each of the radiated patterns, as well the common voltages of the active elements, is calculated by using a genetic algorithm. For each configuration, the currents in the driven and parasitic elements are determined, via their self and mutual impedances, by inversion of the impedance matrix. In the presented examples, the method has been applied to both linear and planar arrays of parallel dipoles that switch the power pattern from a pencil to a flat-topped beam (linear array) or to a footprint pattern (planar array).

In this study, a wireless bio-radar sensor was designed to detect a human heartbeat and respiration signals without direct skin contact. In order to design a wireless bio-radar sensor quantitatively, the signal-to-noise ratio (SNR) in the baseband output of a sensor should be calculated. Therefore, we analyzed the SNR of the wireless bio-radar sensor, considering the signal power attenuation in a human body and all kinds of noise sources. Especially, we measured a residual phase noise of a typical free-running oscillator and used its value for the SNR analysis. Based on these analysis and the measurement results, a compact, low-cost 2.4 GHz direct conversion bio-radar sensor was designed and implemented in a printed circuit board. The demonstrated sensor consists of two printed antennas, a voltage-controlled oscillator, an I/Q demodulator, and analog circuits. The heartbeat and respiration signals acquired from the I/Q channel of the sensor are applied to the digital signal processing circuit using MATLAB. ECG (electrocardiogram), and reference respiration signals are measured simultaneously to evaluate the performance of the sensor. With an output power of 0dBm and a free running oscillator without a phase locked loop circuits, a detection range of 50 cm was measured. Measurement results show that the heart rate and respiration accuracy was very high. Therefore, we verified that a wireless bio-radar sensor could detect heartbeat and respiration well without contact and our SNR analysis could be an effective tool to design a wireless bio-radar sensor.

The increased number of electronic systems in today's car designs requires that each system is EMC compliant prior to vehicle assembly. Each system or component auto supplier is mandated to perform system level EMC testing according to the car manufacturer standards. To ensure high functional integrity of these systems, EMC modeling and simulation are used as a tool. This paper provides an EMC model of a general automotive electrical system. The purpose is to measure, model, and simulate radiated emissions of a test-setup that consists of an electronic control unit ECU, harness, and a load. The model then can be used to optimize the overall system design to achieve EMC compliance or provide a directional improvement to obtain an optimum performance to save cost. Lab measurements are conducted and EMC model is developed according to CISPR25 standards. The model of the printed circuit board PCB and cable harness is accomplished using modeling tools with built-in modeling techniques such as 2D MoM and 3D PEEC. IBIS wave models and SPICE models are connected to simulate circuits and harnesses in time or frequency domain. During simulation, the geometric and electric data are stored together for radiation analysis.

This paper presents two compact ring slot antennas which are suitable for the PCS-1900 and the 2.4/5-GHz triple-band operations. The first antenna consists of three annular ring slots. The outer ring is responsible for exciting the first resonant mode where the middle ring excites the second resonant mode. The inner most rings, through their Y-shape-like slots, create a wide upper operating band by combining the third and fourth resonant modes. To improve this antenna, we have employed circular Photonic Bandgap (PBG) structures in order to obtain a smaller slot antenna with better radiation characteristics. In this design, the cross-polarization level in the E-plane has reduced compared to the first antenna by 5.5 dB, 0.3 dB and 4 dB in three resonant bands. Also, the cross-polarization in H-plane has reduced by an amount of 3 dB. In addition, the obtained results show that the co-polarization patterns are very similar in all three frequency bands. In both cases we have reduced the size of antennas to 56% and 42% respectively, of conventional microstrip slot antennas. The simulation results are verified by measurements.

A novel method for direction-of-arrival (DOA) estimation is proposed. This technique employs the excellent performance of Bartlett method in coherent environments as well as high resolution and low computational complexity of Beamspace MUSIC. Simulation results show that the use of Beamspace MUSIC with Bartlett yields significantly improved performance compared to the original MUSIC especially in highly correlated situations.

A micro electromechanical phase shifter base on the fractal geometries is proposed to work at Ku frequency band with at least 23% lower actuation voltage compared to the simple rectangular membrane counterparts. In this design the membrane of the switch is chosen to be a Koch fractal and then a distributed MEMS phase shifter is set up by cascading a distinct number of these switches. This phase shifter is analyzed to obtain its parameters such as differential phase shift, group delay, and insertion and return loss. It will be shown that this phase shifter could be used as a low loss multi bit phase shifter system because of its low insertion loss and power consumption.

An increasing attention has been concentrated on nondiffracting Bessel beams, due to their novel properties and prospective applications. In order to study their properties entirely, including the transverse modes, the polarization states and the flow of energy, vector analyses should be done. In this paper, based on auxiliary functions of Hertzian vector potential, nondiffracting Bessel beams are analyzed. The useful results are obtained and presented in this paper.

This paper propose a new multiple-input multiple-output (MIMO) signal processing scheme that combines optimum transmit and receive beamforming with the Alamouti space-time block code (STBC) transmission and modifies the decoding process. The scheme uses double antenna array groups to achieve stable performance regardless of direction of arrived (DOA) and angular spread (AS). In a multiuser MIMO communications scenario, the beamforming suppresses co-channel interference (CCI) by maximizing the uplink signal-to-noise-plus-interference-ratio (SINR) and suppress CCI independently while preserving orthogonality of the MIMO channel. It is shown that the beamforming process provides array gain by increasing the bit-error-rate (BER) performance and maximizes the available uplink channel capacity for each user in the presence of CCI.

The WIMAX technology based on air interface standard 802-16 wireless MAN is configured in the same way as a traditional cellular network with base stations using point to multipoint architecture to drive a service over a radius up to several kilometers. The range and the Non Line of Sight (NLOS) ability of WIMAX make the system very attractive for users, but there will be slightly higher BER at low SNR. In this paper, a comparison between the performance of wimax using convolutional code and convolutional product code (CPC) [1] is made. The CPC enables reducing BER at different SNR values compared to the convolutional code. For example, at BER equals 10^-3 for 128 subcarriers, the amount of improvements in SNR is more than 2 dB. Several results are obtained at different modulating schemes (16QAM and 64QAM) and different numbers of sub-carriers (128 and 512).

This paper presents an investigation for the electromagnetic scattering characteristic of the 2-D infinitely long target located above two-layered 1-D rough surfaces. A finite-difference time-domain (FDTD) approach is used in this study, and the uniaxial perfectly matched layer (UPML) medium is adopted for truncation of FDTD lattices, in which the finite-difference equations can be used for the total computation domain by properly choosing the uniaxial parameters. The upper and lower interfaces are characterized with Gaussian statistics for the height and the autocorrelation function. For the composite scattering of infinitely long cylinder and underlying single-layered rough surfaces as an example, the angular distribution of scattering coefficient with different incident angles is calculated and it shows good agreement with the numerical result by the conventional method of moments. And the influence of some parameters related to the twolayered rough surfaces and target on composite scattering coefficient is investigated and discussed in detail.

This paper presents the application of using the macromodels for modeling the interconnections in some fairly complex digital high speed circuits. The analysis which is based on a time domain full wave approach, deals with signal integrity. The results of this simulation are compared with measurements, and sources of error are discussed.

Blind direction of arrival (DOA) estimation algorithms of coherent sources using multi-invariance property is presented in this paper. ESPRIT-like algorithm in [23] can estimate DOA of coherent signal, but its performance is without satisfaction. We reconstruct the received signal to form data model with multi-invariance property, and then multi-invariance ESPRIT and multi-invariance MUSIC algorithms for coherent DOA estimation are proposed in this paper. Our proposed algorithms can resolve the DOAs of coherent signals. They have much better DOA estimation performance than ESPRITlike algorithm. Meanwhile they identify more DOAs than ESPRIT-like algorithm. The simulation results demonstrate their validity.

An ultra-wideband exponential tapered slot antenna with new geometrical gratings, which is fed by a nonuniform CPW-slotline balun that is essentially important for the ultra-wide band characteristic, has been introduced in this paper. The measurement shows that the frequency band is from 1.7 GHz to over 13 GHz, among which the VSWR is below -10 dB except 1.7 GHz around (below -9 dB). The gratings are emphasized to make the antenna to perform better radiation characteristics of a comparatively stable, symmetrical pattern and low side lobes through the operating band as well as obviously higher gain and sharper beam width in the low frequency section in comparison with the one without gratings (more than 3 dB at 1.7 GHz).

This paper presents a formulization of time domain (TD) discrete electromagnetic (EM) solution to provide an effective analysis over a variety of EM problems. This procedure first represents the time responses of EM fields in terms of a set of selected basis functions. Their coefficients are then employed to create matrix-form Maxwell's equations with forms analogous to frequency domain (FD) Maxwell's equations, which allows one to formulate TD solutions via utilizing their corresponding FD solutions that are existing and generally much mature. This work provides general characteristics with parts previously described in the discrete-time EM theory [20, 21] and, most importantly, provides rigorous theoretical derivations in formulating the TD solutions.

In this paper, we improve the Ge-Esselle's (GE's) method and apply it to calculate the multilayered Green's functions in the shielded structures. In the improved GE's method, 1) the poles are first extracted using a recursively contour integration method [1]; 2) then the general pencil-of-function (GPOF) [2] is performed to approximate the part of the spectral-domain Green's functions (with the poles contributions being extracted) just along the real axis of k_ρ plane instead of the rooftop shaped path defined in [3]; 3) Subsequently, the GE's analytical method is employed to obtain the spatial-domain Green's functions. In step 2), a smoothing procedure is also performed here to eliminate the abrupt peak of the sampled spectral-domain Green's function caused by the finite machine accuracy of the poles locations. The numerical results in this paper show that the improved GE's method can accurately and efficiently calculate the Green's functions in the shielded multilayered structure.

We have studied the problem of diffraction of plane waves by a finite slit in an infinitely long soft-hard plane. Analysis is based on the Fourier transform, the Wiener-Hopf technique and the method of steepest descent. The boundary value problem is reduced to a matrix Wiener-Hopf equation which is solved by using the factorization of the kernel matrix. The diffracted field, calculated in the far-field approximation, is shown to be the sum of the fields (separated and interaction fields) produced by the two edges of the slit. Some graphs showing the effects of slit width on the diffracted field produced by two edges of the slit are also plotted.

This work is about evaluating radar performance in detection of targets embedded in a clutter following Non centered chi-2 Gamma distribution model. This model, also called NG-distribution model, is able to fit high resolution sea radar clutter. In this paper, NG model is described. The performances of CA-CFAR radar, namely probability of detection and probability of false alarm, are calculated and closed forms of these probabilities are achieved. In order to evaluate the obtained results, simulation and analytical results are compared. Good matching between these results is achieved.

A compact Pi-structure transformer operating arbitrary dual band is proposed in this paper. To achieve the ideal impedance matching, the exact design formulas with no restrictions are obtained. In addition, it is found that there are infinite solutions for this novel transformer considering the fact that three independent variables exist in two equations. And to verify the design formulas, the reflection characteristics in different cases are shown by numerical simulations. The horizontal length of this transformer is half of the Monzon's dual band transformer. The proposed dual band transformer can be used in many compact dual band components design such as antennas, coupler and power dividers.

This paper studies the correlation of a receiving thin dipole with an arbitrary load in both anechoic chamber (AC) and reverberation chamber (RC). In both cases, the method of moments is employed to calculate the current distributions along a thin dipole induced by external fields. In AC, a plane wave with a fixed incident angle and polarization is illuminated on the dipole; whereas in RC, the field is represented by an appropriate superposition of many incident plane waves with stochastic incident angles, polarizations and phases. Numerical results for the current distributions of a thin dipole with different loads and electrical lengths are presented and discussed in both chambers. It is demonstrated that the ratios with respect to current magnitudes at the arbitrary load of the thin dipole between AC and RC are determined by its directivity. In particular, the ratios with respect to current magnitudes along the entire dipole whose electrical length is less than half a wavelength are nearly constants regardless of the terminating load, which indicates that results obtained in both chambers are well correlated.